Noise at Work

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Noise at Work
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Definitions
Sound Propagation of energy waves travelling
through air, causing sensation of the human
ear (measured in decibels). Noise An
unwanted sound that irritates/disturbs. Noise
levels are measured by taking sound
measurements (dB) and then applying a weighting
factor to account for how loud/audible sound
levels are to the human ear (dB(A)). Frequency Th
e pitch of the sound (high/low) measured in
cycles per second, know as Hertz. High pitch
High frequency. Tone The type of sound
(hissing, rumbling, whistling etc) Intensity The
loudness/volume of the sound
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Octave Band Frequencies
Octave band describes the division of the
frequency range into bands. This can be very
useful when selecting appropriate noise controls
and some are more efficient at determined
frequencies.
The human ear is very sensitive to different
frequencies. The audible frequency range for
humans is generally 20 to 20,000Hz. However our
ability to hear depends on age, health and noise
exposure history.
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Noise Induced Health Effects
The human ear is full of sensitive cells that
allow us to hear sound. Exposure to high or
prolonged levels of noise can have both temporary
and permanent effects on an individuals ability
to hear, impacting not only on their personal
lives, but also on their ability to hear warning
signals at work.
Temporary Threshold Shift Caused by a single,
loud noise such as an explosion, gun shot or
single impact (often causes temporary hearing
loss). Permanent Threshold Shift Continuous,
regular exposure to loud noise, such as machine,
causing permanent hearing damage (Noise Induced
Hearing Loss NIHL) Tinnitus Ringing, whistling,
buzzing sound in the ear, which is irreversible.
This is a distressing condition, leading to lack
of concentration and poor sleep. Stress Unwanted
and irritating noise can increase stress levels
creating safety hazards in that it interferes
with potential warnings and communications.
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Measuring Sound/Noise
Noise levels are measured on a logarithmic scale
by taking sound measurements (dB) and then
applying a weighting factor to account for how
loud/audible sound levels are to the human ear
(dB(A)). When calculating an individuals
personal noise exposure there are different types
of measurement that may be taken, which are
recorded using a Sound Level Meter. Leq Levels
of equivalent noise in the work environment
Lep,d Personal daily noise exposure, usually
calculated over 8 hours Lpeak Highest one off
noise level recorded throughout a given period of
time.
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Combined Noise Sources
Due to the application of the logarithmic scale
in noise measurement, decibels cannot just be
added together to calculate the impact of
combined noise sources.
To apply the information from the table you must
first calculate the differences between he sound
levels to which the person is exposed, then
select the appropriate addition value and add it
to the highest exposure value. Example Person
working in 4 different areas with sound levels
of 90, 89, 87 and 84. Step 1) 90 and 89
difference of 1 add 2.5 to higher value of 90
92.5 (approx 93) Step 2) 87 and 84 difference of
3 add 2 to higher vale of 87 89 Step 3) 93 and
89 difference of 4 add 1.5 to higher value of
93 94.5 (approx 95) Additive Sound Exposure
Level 95 dB(A) 2nd Action Level
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Noise Transmission Pathways
Noise can be transmitted from a source to an
individual through a variety of pathways. Direct
Path When close to the noise source, most noise
is due to direct path transmission Reflected
path Noise is reflected from hard surfaces such
as plaster, brick and structural steel. At less
than 5m distance, reflected noise equal intensity
of direct noise Ground Transmission Vibrations
from the equipment creating the noise travel
through the floor and cause the floor, people and
surrounding air to vibrate Panel
Excitation Ground vibrations cause other
surrounding equipment to vibrate and create
additional noise sources
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Noise Transmission Pathways
Direct Path
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Noise Transmission Pathways
Reflected Path
Hard Ceiling
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Noise Transmission Pathways
Ground Transmission
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Noise Transmission Pathways
Panel Excitation
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Noise Transmission Pathways
Total Experience
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Noise Controls

• The HSE advocates a hierarchy of noise control
  measures. The hierarchy determined the methods of
  control that should be considered and in what
  order.
• Control Noise at Source
• Substitution
• Isolation / Pathway interruption
• Distance
• Active Noise Control
• Hearing Protection the last resort !

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Noise Controls

• Controlling Noise at Source
• Machine related noises are generally caused by
  Impact, Friction or Vibration
• Avoid impacts rubber buffers, bump stops etc
• Damping liquid filling
• Stiffening, clamping or bracing changes
  frequency of noise
• Surface Coatings sound absorption materials
• Exhaust Silencing
• Dynamic balancing of rotating parts reduce
  vibration
• Substitution
• Substituting a process for one that is quieter,
  or altering existing processes
• Shearing is quieter than stamping
• Hydraulic drivers and quieter than pneumatic
• Break stem rivets instead of hammered

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Noise Controls

• Isolation / Pathway interruption
• Isolating people from the noise source or
  interrupting the pathways along which noise is
  transmitted
• Anti-vibration mountings spring feet
• Dampers liquid filling
• Acoustic enclosures surrounding machine/process
• Acoustic shielding partial enclosures
• Absorbing panels interrupts noise path
• Noise refuges noise free enclosure/booth from
  which operators work
• Distance
• Provides good source of control as sound
  dissipates the further you are from the source

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Noise Controls
Hearing Protection / Audiometry As with all
types of PPE, hearing protection should be used
as the last form of defence once all other
control methods have been utilised. There are 2
main types of hearing protection Ear
Plugs Ear Muffs Disposable Non-disposable Ac
oustic wool/foam Hard cups made from soft
foam Flexible inserts Covers ears
externally Colour coded to indicate
protection levels Information from the
manufacturers will confirm the noise attenuation
values (protection levels). These indicate how
much noise reduction can be achieved through the
use of the product. Audiometry is the
measurement of hearing and regular testing helps
determine whether hearing loss is being prevented
through the controls.
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Noise at Work Regulations 2006
Maximum Exposure Limit Value 87 dB(A)

Noise exposure to any employee
(including the use of hearing protection) must be
below 87 dB(A).
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Noise at Work Regulations 2006

• Additional General Duties Requirements
• Reduce the risk of noise exposure to the lowest
  practicable levels
• Records must be kept of noise measurements and
  these must be made available on request
• Records must be kept of hearing tests and these
  must be made available on request
• Company policy on noise control must be made
  available on request
• Employer should implement a Buy Quiet policy
  for plant and equipment

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DMUK Noise at Work
Priority action items
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DMUK Noise at Work
Noise Control Priority Action Items
During 2006 the Health and Safety department will
be working with PEN with the aim of reducing
noise levels throughout the factory to the lowest
practicable levels, through appropriate noise
control measures.
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Noise at Work Key Messages

• Exposure to high/continuous noise levels can
  have permanent health effects
• Lower levels of noise can also irritate and
  disturb, causing problems for communication and
  concentration
• The frequency of the noise source impacts the
  potential health effects
• Noise is transmitted to people by many different
  pathways
• Hierarchy of Noise Controls Control at source
• Substitution
• Isolation / pathway interruption
• Distance
• Active noise control
• Hearing Protection last form of defence !
• Consider combined and additive noise
  levels/sources when changing layouts
• Consider combined and additive noise
  levels/sources when purchasing equipt
• Implement a buy quiet policy for new equipment
• Ensure all equipment is well maintained to avoid
  additional noise from defective equipment